/**
 * Implements hook_page_attachments().
 */
function module_page_attachments(array &$page) {
  $request = \Drupal::request()->getRequestUri();
  $nid = NULL;
  if (substr($request, 0, 6) == '/node/') {
    $nid = substr($request, 6);
  } else {

//не забываем
use Drupal\Core\Database\Database;
use Drupal\Core\Database\Query\Select;
 
//далее просто пример моего запроса
$connection = Database::getConnection();
$sql = new Select('node__field_tags', 'ft', $connection);
$sql->condition('field_tags_target_id', $tids, 'in');
$sql->leftJoin('taxonomy_term_field_data', 'tfd', 'tfd.tid=ft.field_tags_target_id');
$sql->leftJoin('node_field_data','nfd', 'nfd.nid=ft.entity_id');
$sql->fields('ft', array('field_tags_target_id', 'entity_id'));
$sql->fields('tfd', array('name'));

$current_uri = \Drupal::request()->getRequestUri();

function template_preprocess_views_view_field(&$vars) {
  $field_id = $vars['field']->options['id'];
  $views_name = $vars['view']->id();
  $display_name = $vars['view']->getDisplay()->display['id'];
  $vars['theme_hook_original'] =  'views_view_field__' . $views_name . '__' . $display_name . '__' . $field_id;
}

function template_preprocess_views_view_fields(&$vars) {
  $views_name = $vars['view']->id();

map_render:
  js:
    js/infobox.js: {}
    js/markerclusterer.js: {}
    js/map_render.js: {}
  css:
    base:
      css/map_base.css: {}
    layout:
      css/map_layout.css: {}
    component:
      css/map_component.css: {}
    state:
      css/map_state.css: {}
    theme:
      css/map_theme.css: {}

//не сработает
$render_image = '<img src="/my-image.png" />';
$link = Link::fromTextAndUrl($render_image, $url)->toRenderable();
 
//сработает
$render_image = Markup::create('<img src="/my-image.png" />');
$link = Link::fromTextAndUrl($render_image, $url)->toRenderable();

{{ dump(array) }}

{% for article_i,article in articles %}
    Article key : {{ article_i }}
    Article Value : {{ article }}
    {% for key,value in article %}
        Key : {{ key }}
        Value : {{ value }}
    {% endfor %}
{% endfor %}

{# code #}

{% if field is not empty %}
  {{ field }}
{% endif %}

//не забываем
use Drupal\file\Entity\File;
 
 
$file = File::load($image_id);
$variables = array(
  'style_name' => 'thumbnail',
  'uri' => $file->getFileUri(),
);
$image = \Drupal::service('image.factory')->get($variables['uri']);
if ($image->isValid()) {
  $variables['width'] = $image->getWidth();
  $variables['height'] = $image->getHeight();
}
else {
  $variables['width'] = $variables['height'] = NULL;
}
$preset = [
  '#theme' => 'image_style',
  '#width' => $variables['width'],

//с обёрткой
return [
      '#type' => 'markup',
      '#markup' => $this->t('Content of page')
];
 
//без обёртки(аналог MENU_CALLBACK)
return new Response('Content of page');
 
//тоже самое, только будет жёстко кэшироваться.
return new HtmlResponse('Content of page');
 
//Не забываем
use Symfony\Component\HttpFoundation\Response;

//было
variable_set('key','value')
 
//стало
\Drupal::state()->set('key','value');
 
 
//было
variable_get('key','value')
 
//стало
$val = \Drupal::state()->get('key');
 
 
//было
variable_del('key')
 
//стало
$val = \Drupal::state()->delete('key');
 
 
//и даже так ещё стало
$values = [
  'key' => 'value',
  'key2' => 'value2'
];
\Drupal::state()->setMultiple($values);
 
$keys = [
  'key',
  'key2'
];
$pairs = \Drupal::state()->getMultiple($keys);
 
//было
watchdog('type', 'message');
 
//стало